Low power continuous wave photoacoustic microscope for bioimaging applications

A photoacoustic (PA) system based on low power CW laser and microphone was developed. The PA detection was done by a non-contact method using ambient air as an acoustic coupling medium. A resonant chamber coupled to a microphone was used to detect the PA signal. The system uses a He-Ne laser as source of excitation, modulated by an optical chopper. A resolution of 228 lines/mm for light focused by a 40× optical objective was achieved. Methemoglobin, a constituent of interest in blood pattern analysis by forensics, is used as a test sample. High SNR images methemoglobin we produced. The proposed technique is expected to find potential applications in forensics and biomedical analysis.